A company audit showed that of all bills that were sent out, 71% of them were paid on time, 18% were paid up to 30 days late, 9% were paid between 31 and 90 days late, and 2% remained unpaid after 90 days. One bill is selected at random. a) What is the probability that the bill was paid on time? b) What is the probability that the bill was paid late?